CODEWITHSUNDEEP
jsonscalaplayframework
skb
skb

Reputation: 31164

How do I parse JSON requests in my Play project

I am building a simple web server with Scala + Play. I am having trouble figuring out how to accept and deserialize JSON requests into objects of my predefined types. I need help 1) downloading a well-supported JSON package, 2) importing the package in my code to parse the HTTP requests, and 3) actually parsing some JSON.

Here is what I am putting in my SBT file for #1:

libraryDependencies += "org.json4s" %% "json4s-native" % "3.2.9"

Here's how I'm trying to import it for #2:

import org.json4s._
import org.json4s.native.JsonMethods._

Here's where I try to parse some JSON in my action:

package controllers

import play.api._
import play.api.mvc._
import play.api.libs.json.Json
import org.json4s._
import org.json4s.native.JsonMethods._

object Application extends Controller {
  case class Credentials(username: String, password: String)

  def login = Action { request =>
      Ok(Json.obj("message" -> "You tried to log in as: " + parse(request.body).extract[Credentials].username))
  }
}

Can anyone tell me what I am doing wrong? I am getting an error at runtime which says: "play.PlayExceptions$CompilationException: Compilation error[controllers.Application.parse.type does not take parameters]"

Upvotes: 1

Views: 1339

Answers (1)

Michael Zajac
Michael Zajac

Reputation: 55569

You're suffering from namespace pollution. Your Application controller inherits a parse object from the play.api.mvc.Controller trait, and import org.json4s.native.JsonMethods._ includes its own parse in the namespace. I'm surprised this even compiles. Making it more explicit will work. Drop the wildcard from the import, and explicitly call JsonMethods.parse.

As the commments suggest, this is all really unnecessary. Play's built in json libraries work pretty well, so I also suggest you read up on them and use them. There are plenty of other SO posts related to Play JSON as well.

Upvotes: 5

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